Air conditioning unit and control



1957 s. J-. LEVINE AIR CONDITIONING UNIT AND CONTROL Original Filed Jan.5, 1952 Inventor: Samuel J. Levine Hi5 Attorney.

Unite States Patent Ofifice 2,808,488 Patented Oct. 1, 1957 AIRcoNnrrroNlNo UNIT AND CONTROL Samuel J. Levine, l est Grange N. 3.,assignor to General Electric Company, a corporation of New York Originalapplication January 5, 1952, Serial No. 265,153, now Patent No.2,711,681, dated June 21, 1955. Di vided and this appiication September17, 1954, Serial No. 456,741

3 Claims. (Cl. 200-440) This application is a division of applicationSerial No. 265,138, filed January 5, 1952 (now Patent 2,711,681), in thename of Samuel J. Levine and assigned to the same assignee as thepresent invention.

This invention relates to air conditioning apparatus and particularly toair conditioning units for ofiice buildings and the like.

Office buildings, for example, may be provided with air conditioningunits supplied with preconditioned air from a central plant but alsoproviding individual control for the oliices through the operation ofblowers installed in units in each omce for circulating air from thecentral plant and from the room over heat transfer surfaces in the unit.It is desirable that all the units in the building be under control ofthe central plant so that the entire system may be shut down from thecentral plant. Such shutdowns may be desirable in ofiice buildings, forexample, over the week end; however, it is also desirable thatindividual ofiices be conditioned although the entire system is not inoperation so that such offices in use when the over-all system is not inoperation may be air conditioned. Accordingly, it is an object of thisinvention to provide an air conditioning system including individuallycontrolled units for rooms of the building and providing over-allcontrol from the central plant and a selectively controllablearrangement for conditioning individual rooms when the over-all plant isnot in operation.

It is another object of this invention to provide an improved controlsystem for air conditioning units.

It is a further object of this invention to provide an improvedcontroldevice for air conditioning units which is simple in operation andaffords selective control of the unit.

Further objects and advantages of the invention will become apparent asthe following description proceeds, and the features of novelty whichcharacterize the invention will be pointed out with particularity in theclaims anmated to and forming a part of this specification.

In carrying out the objects of this invention, an air conditioning unitof the type comprising a heat transfer surface and electric motor drivenblowers for circulating air over the surface is arranged to receive airunder pressure from a suitable source and is provided with a controlmechanism for actuating the blower motor upon the occurrence of apredetermined pressure in the air supply. The control further includes amanually operated element for starting the motor in the absence of airpressure in the supply, this latter control being biased to its neutralposition and being retained in its motor actuating position by alatching mechanism which is released whenever air pressure is restoredin the inlet to the unit. An installation of a plurality of such unitsmay thus be controlled by supplying air under pressure to all of theunits, but individual units may be actuated in the absence of suchpressure by operation or" the manual control. A further selectivecontrol is provided so that the motor may be stopped even though the airpressure control is actuated.

For a better understanding of this invention, reference may be had tothe accompanying drawing in which Fig. 1 is a front elevation, partly insection, of an air conditioning unit embodying this invention; Figs. 2and 3 are end views or the unit of Fig. 1; Fig. 4 is a diagrammatic viewof a plurality of units of the type shown in Fig. 1 arranged in amultizone installation; Figs. 5 and 6 are enlarged elevation and sideviews, respectively, of the control mechanism employed in the unit ofFig. 1; Fig. 7 is a diagrammatic illustration of the electric circuitemployed in the conditioner of Fig. 1; and Figs. 8 and 9 are enlargeddetail views, taken On the line 88 of Fig. 5, illustrating the twopositions of the manual control switch of the control.

Referring now to the drawing, the air conditioning unit shown in Figs.1, 2 and 3 comprises a casing 10 in the upper portion of which isarranged a heat transfer unit 11 of the finned coil type arranged toreceive heat transfer liquid from a suitable supply through intake anddischarge connections 12 and 13. Air may be circulated over the unit itby operation of a pair of centrifugal blowers 14 and 15 driven by anelectric motor 16, as indicated by dotted lines in Fig. 1. Room air isadmitted to the unit through an opening 17 at the bottom of the casingand flows throu h a filter 18 to the blower inlets. Fresh air,preferably conditioned in the central plant, is supplied under pressurethrough an inlet 19 and flows through a series of perforated battleplates 20 and into an elongated silencer tube 21 from which it flowsinto the space below the filter 18, as indicated at 22. Thus the freshair is mixed with the return air and enters the blower inlets to becirculated over the heat transfer surface 11.

The unit may be employed either for heating or cooling, suitableequipment being provided in the central plant to supply either heatingor cooling liquid to the unit 11. When the unit is employed for cooling,moisture condensed on the surface of the unit 11 flows into a trough 23and then through a drain connection 24 to a collecting funnel 25 underwhich may be placed a container or plumb ing connection (not shown).When the unit is employed for heating, the air supplied under pressurefrom the central plant may be preheated, and when the system is employedfor cooling, this air may be precooled thereby removing the majorportion of the moisture from the fresh air before it is distributed tothe units.

The general arrangement of the units in an ofiice building, for example,is shown in Fig. 4 where three units 10 have been illustrated arrangedto receive conditioned air under pressure from a central plant 26through a supply duct 27 connected through risers 23 to the inlets 19 ofthe units it). Each of the units is provided with a control device 29which is arranged to ener ize the motor 16 Whenever air is suppliedunder pressure to the inlet 19 and further, in the event that air is notbeing lied, these controls are provided with manually adjustable membersto operate the motors although central plant air is not available. Thecentral plant arrangement for supplying heating or cooling fluid to theheat transfer units 11 has not been illustrated in order to avoidfurther complication of the drawing. It will be apparent that all of theunits may be conditioned for operation by supplying air under pressurethrough the conduit 27, but that in the event the central airconditioning system is shut down, as over a week end, individual ofiicesmay be controlled manually.

The control 29 is provided with a pressure tube or connection 39, shownin Figs. 1 and 2, which provides communication between the control andthe air supply inlet 19. The details of the control are shown in Figs. 5and 6. The pressure tube 30 is connected to a chamber 32 within anexpansible chamber device 33 which includes a movable diaphragm 34biased to its low pressure position by a spring 35 mounted between thediaphragm and a wall 36 2,soe,ass

of the device 33. The chamber 32 is formed by a wall 37 of the device 33which is mounted in engagement with the back wall of the casing of thedevice 29 indicated at 38. An electric switch 39 is mounted on a bracket40 on the wall 36 and includes a switch arm 4]; arranged in the path ofa plunger 42 mounted on the diaphragm When a predetermined pressureprevails in the chamber 32, the plunger 42 moves toward and engages thearm 41 and moves it to the left to actuate the switch. The arm 41 isresiliently urged toward its right-hand position, as illustrated in Fig.6, by a suitable spring biasing means (not shown), the switch being ofthe well-known snap acting type which is biased to its open position.The switch 39 is connected in the circuit of the motor to in the mannerillustrated in Fig. 7. The motor 16 may be supplied with current fromlines 45 through the switch 39 and a manual switch 46, shown in its offposition. When the switch 46 engages either of a pair of terminals 47and 43 of a reactor 49, the motor is connected across the lines 45 uponclosing the switch 39. When the switch 46 engages the contact 47 themotor is operated at full speed, and when it engages the contact 48 thereactor 49 is placed in series with the motor which then runs at reducedspeed.

During periods when the majority of the offices in the building areunoccupied and there is no demand for heating, it may happen that insevere winter weather the temperature becomes abnormally low. It isdesirable to prevent reduction of the temperature below somepredetermined value and an arrangement is provided so that the fans maybe started when room temperatures fall too low. The heat exchange coilis supplied with warm water at all times, and in order to circulate theair over the coil and prevent too great a reduction in room temperaturea thermostat Si) is provided in the control which engages a contact 51at the desired minimum temperature and connects the motor for reducedspeed operation through the reactor 49 even though the switches 39 and46 are open. By preventing too great a reduction in temperature in theunused rooms, the general ambient temperature within the building isprevented from falling to too low a value.

From the foregoing, it is readily apparent that all of the units in abuilding such as that illustrated in Fig. 4 may be controlled bysupplying air under pressure through the duct 27; however, during theidle periods of the overall system when air is not being supplied underpressure from outside the room it may be desirable to operate anindividual unit, and for this purpose a manual control having a knob 52is provided to close the switch 39 al though the diaphragm 34 is in itsright-hand position and the plunger 42 out of engagement with theswitch. The knob 52 is secured to a shaft 53 mounted in a bracket 54secured to the wall 36 of the device 33. A cam 56 is secured to the endof the rod 53 and acts as a stop against which the switch arm 41 bearswhen the plunger 42 is disengaged. The cam 56 is eccentric in form, asillustrated in Figs. 8 and 9, its normal position being shown in Fig. 8and corresponding to its position as shown in Figs. and 6. The cam 56 isurged to this position by a coil spring 57 having one end engaging thebracket 54 and its other end hooked about a post 58 on the rod 53. Thisspring biases the cam 56 to its position as shown in Fig. 8 wherein thecam engages the plate 36 at 59. The cam 56 includes a notched orrelieved portion 60 in its periphery remote from the rod 53, and whenthe knob 52 is turned to rotate the rod 53 in a clockwise direction, asviewed in Fig. 8, the notch 60 engages the switch arm 41 and therebyretains the cam 56 in the position shown in Fig. 9, the arm 41 beingurged against the cam by the bias of the switch arm and preventingrotation of the shaft 53. Thus the motor may be actuated by closing theswitch 39 even though air under pressure is not available at the inlet19. This enables the occupant of an individual room to control thecirculation of air in that room whether or not the central plant airsupply is in operation. Whenever the central plant is again placed inoperation, the plunger 42 moves the switch arm 41 to the left out ofengagement with the cam, which thereupon is returned to its position ofFig. 8 by the biasing spring 57, thereby restoring the unit to automaticcontrol. it will be understood that the switch arm 41 is moved to itsswitch closing position by movement of the cam 56 to the position asshown in Fig. 9 but may be urged beyond the position for initial closingof the switch by the switch bias upon operation of the plunger 42.

From the foregoing, it is readily apparent that a simple and effectivearrangement has been provided for controlling air conditioning units inmultizone installations while making possible individual control of theunits when the central plant automatic control is not in operation,thereby providing a system which is flexible in operation, particularlyfor installations involving a great many separate zones normallysupplied with fresh air from a common central source.

While a particular embodiment of the invention has been illustratedincluding specific details of structure, modifications will occur tothose skilled in the art and it is not desired to limit the invention tothe specific structure illustrated, and it is intended to cover by theappended claims all modifications which fall within the spirit and scopeof the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

l. A pressure responsive switching mechanism comprising an electricswitch having an operating arm, an expansible chamber device having amovable wall member, means dependent upon a predetermined fluid pressurein said device for utilizing movement of said wall member to actuatesaid switch arm, means for biasing said arm against such movement, amovable stop for said switch arm having a first position for limitingthe movement of the arm by said biasing means of said arm, means formoving said stop to a second position against said biasing means toactuate said switch, spring means for biasing said stop to said firstposition, and means on said stop for engaging said switch arm andretaining said stop in said second position and affording release ofsaid stop and return to said first position upon operation of saidswitch arm by said expansible chamber device.

2. A pressure responsive switching mechanism comprising an electricswitch having an operating arm, an expansible chamber device having amovable wall member, means dependent upon a predetermined fluid pressurein said device for utilizing movement of said wall member to actuatesaid switch arm, means for biasing said arm against such movement, arotatable stop biased to a first position in the path of said switch armfor limiting the movement of said arm by the biasing means of said arm,means for rotating said stop to a second position to move said armagainst its biasing means for actuating said switch, and a catch on saidstop for engaging said arm in the second position of said stop to retainsaid switch in its actuated position, said pressure dependent meansbeing arranged to move said switch arm out of engagement with said catchwhereby said stop is returned to its first position upon a predeterminedmovement of said movable wall member.

3. A pressure responsive switching mechanism comprising an electricswitch having an operating arm and means biasing said arm to its switchopening position, said arm being movable from its switch openingposition to a switch closing position and affording further movement ofthe arm after the switch has been closed, an expansible chamber devicehaving a movable wall member, means dependent upon a predetermined fluidpressure in said device for utilizing movement of said wall member-toactuate said switch arm against the bias thereof, a movable stop forsaid switch arm having a first position for limiting the movement ofsaid arm in the switch opening direction, means for moving said stop toa second position to move said switch arm to its switch closingposition, means for biasing said stop to its first position, and meansutilizing engagement of said stop and said switch arm in the secondposition of said stop for retaining said stop in said second positionand for releasing said stop upon further movement of said arm beyondsaid switch opening position by operation of said expansible chamberdevice.

References Cited in the file of this patent UNITED STATES PATENTS SundhJuly 14, 1903 Bowar Ian. 12, 1951 Greenawalt Mar. 2, 1954 Senn Mar. 9,1954

